Condenser temperature compensation means



Dec. 13, 1938. M. v. WEISS Y CONDENSER TEMPERATURE COMPENSATION MEANS Filed Aug. 10, 1937 ATTORNEY INVENTOR f i I Patented Dec. 13, 1938' UNITED STATES PATENT OFFICE v CONDENSER TEMPERATURE COWS- TION MEANS Melvin v. Weiss, Baddoniield, n; 1., assignma Radio Condenser Comm, Camden, N. 1.

Application August 1837, Serial No. 158,392

This invention relates to an electrical condenser such as is used in radio receiving sets.

It frequently happens that such radio receiving sets are subjected to wide variations in temperas ture, and because of this, it is highly desirable that the component parts making up a tunable circuit, such as the tuning condenser and coil associated therewith, have a very low or zero temperature coefllcient. In practice it is impossible 10 to provide a coil and other parts having a zero temperature coemcient, and it is therefore the principal object of my present invention to provide a condenser having a negative temperature coeiiicient which will automatically balance out the positive coefllcient of the other componentassociated with the stator elements making up a unit condenser.

Figure 2 is a sectional view on the line 2-2 of Figure l, of a two-gang condenser.

Figure 3 is a perspective view of one end of a support member carrying the compensating means Elgure c is a plan view of the support plate shown in Figure 2. g

. Figure 5 is a view on a reduced scale of a sunport plate such as adapted for use in a four-ga s condenser.

In the various views, wherein like numbers refer to corresponding parts, I is a plate element of a stator group making up a condenser, the rotor plates and other details not being shown. 2 and l are the end plates oi! the condenser frame. 0!:

the bottom portion of the end plates I and I, a

support member 4 is attached. The support member 4 has notches s and s at its opposite ends. Intermediate these notches II and I, the sides I and I of the support member are bent over to stifien the support, thereby forming a channelshaped member. Oneend 8 is bent over andhas one or more holes to therein adapted to receive screws II for fastening the end ofthe support to one .of the end plates, such as I.

The opposite end of the support l preierably has an oblong hole It to receive a screw adapted toscrew into the bracket l4 fastened to the end plate 2 in any satisfactory manner as by one or more rivets II. The reason for theoblong hole I! is so that the support may be readily attached to the frame of the condenser without applying any strain thereto, or having any strain applied to it through any slight inaccuracies in the manufacture of theframe.

The support 4 is provided with a hole It adapted to receive an adjusting screw II which is a threaded into a bushing J8 riveted to a bimetallic plate IO composed of two sheets of different kinds of metal, such as ordinarily used in making thermostatic material. Riveted to the plate 4, in the holes 26- and '21, are studs Ill and 10 2-l-considering' a single-unit condenser-while the opposite ends of these studs are positioned respectively in bushings It and 23, likewise rivetad or otherwise securely fastened to the thermostatic plate i9. 15

Associated with each'of the studs 20 and and the bushings-22 aind 23, are springs 25 .and 2! which are under compression between the support t and the plate is. The'studs 20 and ii are used :to prevent turning of the plate 59 on the no support, as well as to prevent wobble thereof. while the springs 24 and 25 act to hold the plate is away from the support and to make the plate follow the adjustment of the screw II. There springs also act to prevent any vibration of 5 the plate i9. I As will be seen from Figure 1, the plate is is positioned longitudinally closely adjacent the bottom edges of the stator element. and is made to generally conform to the shape of these bottom so edges. so that the capacity of the condenser may be slightly varied by movement of the plate ll,

which isautomatically.responsive to changes in temperature.

To remove, as far as possible, any changes in 35 the variation of the temperature of the support I, this is made out of a material having a very low or zero temperature coefllcient, such as Invar steel, which isa composition of'nickel and iron, wherein the nickel may of the order of 35%. 4 Likewise, the adjusting. screw II, is made of the same or similar material, and the guide studs 1| and II and their cooperative bushings 2i and 2! may also be made 0! similar material, although it is not absolutely necessary, in all cases, that 45 these particular parts be so constructed.

In the assembly of the thermostatic b t-metallic plate it, the metal having the higher thermal expansion is placed adiacent'the edges of the.

II stator elements so that changesin. temperatureso willcausetheplatetobendinthedirectionof the small arrows, thus lowering the capacity between the stator elements and the plate II, and

hence giving a negative coefllcient which, as previouslyexplainednendstobalancaoutthepom u tive ooeflicient of the other components in the tunable circuit in which the condenser is used.

It will be obvious that the mechanical details for carrying out my invention may be changed without departing from the spirit thereof or the scope ofthe appended claims.

What I claim is:

1. Temperature compensation means for an electrical condenser having a frame carrying stator and rotor elements; including a support carried by the frame across the bottom thereof and having a very low temperature coefficient, a plate of thermostatic metal carried by said support but spaced a short distance from said stator elements and overlying a considerable portion of the adjacent edges of the stator element, means for adjusting the position of said plate, said adjusting means being made of a material having a very low temperature coefficient, while the plate itself is capable of automatically changing the capacity of the condenser with changes in temperature.

2. Temperature compensating means for an electrical condenser as set forth in claim 1, further characterized in that said support carries means independent of the adjusting means for preventing turning and wobbling of the thermo static plate.

3. Temperature compensating means for an electrical condenser as set forth in claim 1, further characterized in that said support carries on opposite sides of said adjusting means, guide pins having ends slidably located in bushings carried by the thermostatic plate for preventing turning and wobbling of the plate.

4. Temperature compensating means for an electrical condenser as set forth in claim 1, further characterized in that said support carries means independent of the adjusting means for preventing turning and wobbling of the thermostatic plate, and further means co-operatively positioned between the support and thermostatic plate and laterally spaced from said adjusting means to prevent vibration thereof.

5. Temperature compensation means for an electrical condenser having a frame carrying stator and rotor elements; including a support carried by the frame across the bottom thereof and having a very low temperature coemcient, a bi-metallic thermo-couple plate carried by said support by means having very low temperature coefficient characteristics so as to overlie in spaced relation a considerable area of the edges of said stator elements, said plate being capable of automatically changing the capacity of the condenser with changes in temperature.

6. Temperature compensating means for an electrical condenser as set forth in claim 5, further characterized in that means areprovided for adjusting the position of, said plate with respect to the stator elements, and further means independent of the adjusting means for preventing turning and wobble of the plate.

7. Temperature compensation means for an electrical condenser having a frame carrying stator and rotor elements; including a support carried by the frame across the bottom thereof and having a very low temperature coeflicient, a bi-metallic plate extending generally longitudinally along the bottom edges of the stator elements, a threaded bushing centrally fastened to said plate, an adjusting screw shouldered on said support and going into the threaded bushing, at least the screw being made of material having a zero or very low'temperature coefficient, bushings in the plate spaced, one on each side of said centrally located one, guide studs anchored to said support and having ends fitting in said spaced bushings and a compressed spring located between the support and plate in association with each stud and its .bushing for the Purposes described.

MELVIN V. WEISS. 

